Niko is right about the cleaning is mine has too much algae inside, which is common in the bak pak since it is a clear plastic, it does not skim well. Also the ventri port I have attached to the maxijet clogged easily, and for me did not allow enough gph into the skimmer. If your ventri skimmer is like mine it has slits around the cone but these do not enter into the powerhead so the only water entering was through 3 tiny slits near the air tube. So I took the funnel cone thing that makes the inlet larger, it came with the maxi jet, and attached it to inlet and ventri. The ventri slides all the way into this adapter so all those slits are now allowing more water/air into the skimmer.